الفهرس 
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Abstract
Chlorella sp was purificated by culturing on solid Bold Basal Medium (BBM) and growth curve was estimated under conditions (at 26˚C, 35.1 µ.mol/m2/s1 cool white fluorescent lamps with light/dark cycle 16h/8h and continuous sterilized (0.22 µm filter) air for mixing ). Culture density at 440nm and number of cells was measured every 24h, the highest number of cells and culture density in day seven. The isolated algal species were carefully examined under a light microscope and screened for different morphological characteristics and identified as Chlorella vulgaris.Three isolates of bacteria were purified by culturing on solid nutrient medium until single colony formation. The growth curve was estimated for each one under conditions (26°C, 35.1 µ.mol/.m2/s1 cool white fluorescent lamps with shaking at 120 rpm), and culture density at 600nm was measured every one hour. Stationary phase was estimated after 24h. Also, three bacterial isolates were identified by analyzing the sequence of the 16S rRNA gene. The bacterial isolates P3, P4 and P7 showing closest similarity to Bacillus amyloliquefaciens, Pseudomonas rhizosphaerae and Pseudomonas aeruginosa respectively.In order to study the effect of each type of bacteria on Chlorella and to know which one had a stimulating effect, pellets of bacteria were cultivated in Chlorella culture in three ratios (1 algae:1 bacteria as v: v), (1 algae:5 bacteria as v: v) and (1 algae:10 bacteria as v: v). It was found that Pseudomonas rhizosphaerae bacterium (1 algae:5 bacteria as v: v) had a growth-promoting effect on C. vulgaris, causing cell count to be increased six times greater than that of C. vulgaris axenic culture. Unlik both Chlorella cocultured with P3 and P7.In addition, strains of the bacteria and C. vulgaris were screened for their ability to produce indole acetic acid (IAA). It was found that IAA was produced in greater quantity in NB containing Tryptophan than in NB. Pseudomonas rhizosphaerae strain has superiority in IAA productivity during culturing in NB containing Tryptophan compared to NB and recycled BBM (1.156±0.0097µǥ/ml, 1.064±0.0045µǥ/ml and 1.033±0.003 µǥ/ml), respectively. And C. vulgaris produce IAA 0.987±0.0117 µǥ/ml So, Pseudomonas rhizosphaerae had been studied more closely.C. vulgaris was cocultured in supernatant of Pseudomonas rhizosphaerae also C. vulgaris cultured with external IAA equal to produce by Pseudomonas rhizosphaerae. And coculture C. vulgaris with Pseudomonas rhizosphaerae in three ratios. It was found that the highest cell number of C. vulgaris growing in coculture with Pseudomonas rhizosphaerae (1 algae:5 bacteria as v: v), although the highest culture density was investigated in the C. vulgaris cocultured in the supernatant. Lipid and pigments were measured for each treatment. The highest ratios of chlorophyll a, chlorophyll b and carotenoid were in algae treated with P4 strain (1 algae:5 bacteria as v: v) recorded 2.447±0.109, 1.887 ±0.118 and 2.686±0.051 µg/ml respectively. Interestingly, the lipid productivity by C. vulgaris was the highest in the presence of IAA compared to axenic culture, being 1.608±0.124, 1.176±0.164 g/l/day, respectively.